An ink jet recording method has become widely used from the viewpoint that recording can be carried out on various recording materials, the hardware (device) is relatively inexpensive and compact and is superior in quietness. With recent developments of high-resolution ink jet printers, hardware (device) and various ink jet recording media, so-called “photo-like” high quality images have become possible.
As an ink jet recording medium, a recording material having high glossiness and color saturation and good ink absorbance is needed from the viewpoint of improving photographic feel. In order to satisfy these characteristics, ultrafine particles having an average primary particle diameter of 50 nm or less are suitable and, for example, vapor phase method silica or alumina sol is preferably used. As specific examples of such media, recording materials obtained by coating a paper support with a silicon-containing pigment containing, for example, silica, together with an aqueous binder are known (see, for example, Japanese Patent Application Laid-Open (JP-A) Nos. 55-51583, 56-157, 57-107879, 57-107880, 59-230787, 62-160277, 62-184879, 62-183382, and 64-11877).
As an ink jet recording material to which glossiness is provided a recording material obtained by a method in which a solution containing a binder, a pigment and a nonionic surfactant is cast (see, for example, JP-A No. 2-113986), and a recording material obtained by a method in which the outermost surface is treated using an aqueous solution containing a cationic polymer electrolyte and then colloidal silica is cast (see, for example, JP-A No. 2-274587) are proposed.
Also, paper is generally used as the support constituting the aforementioned recording materials wherein the paper itself is made to have a function as an ink absorbing layer.
However, in recent years, photo-like recording materials having texture similar to that of a silver salt photographic printing paper are in demand. Since recording materials using a paper support have problems concerning, for example, glossiness, texture, water resistance, and cockling (wrinkles or waving) after recording, resin laminated paper (polyolefin resin coated paper) obtained by laminating a polyolefin resin such as polyethylene on both sides of paper has become widely used (see, for example, JP-A Nos. 13-270232, 13-96898, 13-63205, 12-351270, and 12-522649).
The polyolefin resin coated paper as mentioned above is generally used as silver salt photographic printing paper and is most suitable in making a recording medium having, particularly, a photographic feel in terms of touch and strength as compared with synthetic films represented by a polyethylene terephthalate film.
On the other hand, a dispersion solution of ultrafine particles having an average primary particle diameter of 50 nm or less has poor dispersion stability, causing a problem in that these fine particles tend to be coagulated. Therefore, in the case of using such a dispersion solution of ultrafine particles to prepare a coating solution for forming an ink-receiving layer constituting an ink jet recording medium, these fine particles tend to coagulate due to unstable dispersion, which tends to cause occurrences of cissing and stripe-like coating defects and reduced in ink absorbance.
When a silica dispersion solution is prepared using silica microparticles as ultrafine particles, usually these silica microparticles are primarily dispersed (premixing or pre-dispersing) in a dispersion medium (water, an organic solvent or a mixture of these materials) to form a silica microparticle slurry and then this silica microparticle slurry is secondarily dispersed using a dispersing machine such as a sand mill, ball mill or sand grinder. However, the particle size of the silica dispersion solution prepared using a dispersing machine such as a ball mill or sand grinder is large, and also the dispersion solution is less transparent. Therefore, an ink jet recording medium using this dispersion solution fails to obtain a sufficiently satisfactory gloss level.
In relation to the above, technologies for improving glossiness and image clarity by improving the smoothness of a support and an ink-receiving layer constituting an ink jet recording medium are disclosed (see, for example, JP-A Nos. 2004-284148, 2004-249708, 2004-195781, and 8-11423). The glossiness has been regarded as a measure of gloss from long ago, and image clarity is utilized currently as an index for determining gloss feel.